Heat-set container and mold system thereof

ABSTRACT

A heat-set container that defines a longitudinal axis is disclosed that includes a finish and a sidewall portion extending from the finish. The container also includes a base portion extending from the sidewall portion and enclosing said sidewall portion to form a volume therein for retaining a commodity. The base portion has a plurality of contact surfaces for supporting the container. The plurality of contact surfaces are spaced away from each other about the longitudinal axis. Also, the container includes a central pushup portion disposed in the base portion and extending generally toward the finish. The central pushup portion is substantially centered on the longitudinal axis, and the central pushup portion is moveable in response to internal vacuum pressure to decrease the volume.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/529,289, filed on Aug. 31, 2011. The entire disclosure of the aboveapplication is incorporated herein by reference.

FIELD

This disclosure generally relates to containers for retaining acommodity, such as a solid or liquid commodity. More specifically, thisdisclosure relates to a container having an optimized base design toprovide a balanced vacuum and pressure response, while minimizingcontainer weight.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art. This section alsoprovides a general summary of the disclosure, and is not a comprehensivedisclosure of its full scope or all of its features.

As a result of environmental and other concerns, plastic containers,more specifically polyester and even more specifically polyethyleneterephthalate (PET) containers are now being used more than ever topackage numerous commodities previously supplied in glass containers.Manufacturers and fillers, as well as consumers, have recognized thatPET containers are lightweight, inexpensive, recyclable andmanufacturable in large quantities.

Blow-molded plastic containers have become commonplace in packagingnumerous commodities. PET is a crystallizable polymer, meaning that itis available in an amorphous form or a semi-crystalline form. Theability of a PET container to maintain its material integrity relates tothe percentage of the PET container in crystalline form, also known asthe “crystallinity” of the PET container.

The following equation defines the percentage of crystallinity as avolume fraction:

${\% \mspace{14mu} {Crystallinity}} = {\left( \frac{\rho - \rho_{a}}{\rho_{c} - \rho_{a}} \right) \times 100}$

where ρ is the density of the PET material; ρa is the density of pureamorphous PET material (1.333 g/cc); and ρc is the density of purecrystalline material (1.455 g/cc).

Container manufacturers use mechanical processing and thermal processingto increase the PET polymer crystallinity of a container. Mechanicalprocessing involves orienting the amorphous material to achieve strainhardening. This processing commonly involves stretching an injectionmolded PET preform along a longitudinal axis and expanding the PETpreform along a transverse or radial axis to form a PET container. Thecombination promotes what manufacturers define as biaxial orientation ofthe molecular structure in the container. Manufacturers of PETcontainers currently use mechanical processing to produce PET containershaving approximately 20% crystallinity in the container's sidewall.

Thermal processing involves heating the material (either amorphous orsemi-crystalline) to promote crystal growth. On amorphous material,thermal processing of PET material results in a spherulitic morphologythat interferes with the transmission of light. In other words, theresulting crystalline material is opaque, and thus, generallyundesirable. Used after mechanical processing, however, thermalprocessing results in higher crystallinity and excellent clarity forthose portions of the container having biaxial molecular orientation.The thermal processing of an oriented PET container, which is known asheat setting, typically includes blow molding a PET preform against amold heated to a temperature of approximately 250° F.-350° F.(approximately 121° C.-177° C.), and holding the blown container againstthe heated mold for approximately two (2) to five (5) seconds.Manufacturers of PET juice bottles, which must be hot-filled atapproximately 185° F. (85° C.), currently use heat setting to producePET bottles having an overall crystallinity in the range ofapproximately 25% -35%.

Unfortunately, with some applications, as PET containers for hot fillapplications become lighter in material weight (aka container gramweight), it becomes increasingly difficult to create functional designsthat can simultaneously resist fill pressures, absorb vacuum pressures,and withstand top loading forces. According to the principles of thepresent teachings, the problem of expansion under the pressure caused bythe hot fill process is improved by creating unique vacuum/label panelgeometry that resists expansion, maintains shape, and shrinks back toapproximately the original starting volume due to vacuum generatedduring the product cooling phase.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

SUMMARY

A heat-set container that defines a longitudinal axis is disclosed thatincludes a finish and a sidewall portion extending from the finish. Thecontainer also includes a base portion extending from the sidewallportion and enclosing said sidewall portion to form a volume therein forretaining a commodity. The base portion has a plurality of contactsurfaces for supporting the container. The plurality of contact surfacesare spaced away from each other about the longitudinal axis. Also, thecontainer includes a central pushup portion disposed in the base portionand extending generally toward the finish. The central pushup portion issubstantially centered on the longitudinal axis, and the central pushupportion is moveable in response to internal vacuum pressure to decreasethe volume.

A mold system is also disclosed for forming a heat-set container havinga central pushup portion disposed in a base portion thereof. The centralpushup portion is substantially centered on a longitudinal axis of thecontainer and extends generally toward an interior of the container. Thebase portion has a plurality of contact surfaces for supporting thecontainer. The plurality of contact surfaces are spaced away from eachother about the longitudinal axis. The base portion is bound by asidewall portion to hold a commodity. The mold system comprises asidewall system for molding the sidewall portion of the container and abase system for molding the base portion of the container. The basesystem is operable to form an entirety of the base portion of thecontainer including the central pushup portion and the plurality ofcontact surfaces.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIGS. 1-5 are views illustrating exemplary embodiments of a containerwith various features of the present teachings, wherein FIG. 1 is aperspective view, FIG. 2 is a side view, FIG. 3 is a front view, FIG. 4is a bottom view, and FIG. 5 is a section view taken along the line 5-5of FIG. 4;

FIGS. 6-9 are views illustrating additional exemplary embodiments of acontainer with various features of the present teachings, wherein FIG. 6is a perspective view, FIG. 7 is a side view, FIG. 8 is a bottom view,and FIG. 9 is a section view taken along the line 9-9 of FIG. 8;

FIGS. 10-13 are views illustrating additional exemplary embodiments of acontainer with various features of the present teachings, wherein FIG.10 is a perspective view, FIG. 11 is a side view, FIG. 12 is a bottomview, and FIG. 13 is a section view taken along the line 13-13 of FIG.12;

FIGS. 14-17 are views illustrating additional exemplary embodiments of acontainer with various features of the present teachings, wherein FIG.14 is a perspective view, FIG. 15 is a side view, FIG. 16 is a bottomview, and FIG. 17 is a section view taken along the line 17-17 of FIG.16;

FIGS. 18 and 19 are views illustrating additional exemplary embodimentsof a container with various features of the present teachings, whereinFIG. 18 is a bottom view and FIG. 19 is a section view taken along theline 19-19 of FIG. 18;

FIGS. 20 and 21 are views illustrating additional exemplary embodimentsof a container with various features of the present teachings, whereinFIG. 20 is a bottom view and FIG. 21 is a section view taken along theline 21-21 of FIG. 20;

FIGS. 22 and 23 are views illustrating additional exemplary embodimentsof a container with various features of the present teachings, whereinFIG. 22 is a bottom view and FIG. 23 is a section view taken along theline 23-23 of FIG. 22;

FIGS. 24 and 25 are views illustrating additional exemplary embodimentsof a container with various features of the present teachings, whereinFIG. 24 is a bottom view and FIG. 25 is a section view taken along theline 25-25 of FIG. 24;

FIGS. 26A and 26B are section and side views, respectively, of a baseportion of a container according to additional exemplary embodiments ofthe present disclosure;

FIGS. 27A and 27B are section and side views, respectively, of a baseportion of a container according to additional exemplary embodiments ofthe present disclosure;

FIGS. 28A and 28B are front and side views, respectively, of a generallyrectangular container according to additional exemplary embodiments ofthe present disclosure;

FIGS. 29A and 29B are perspective and bottom views, respectively, of agenerally cylindrical container according to additional exemplaryembodiments of the present disclosure;

FIGS. 30A and 30B are perspective and bottom views, respectively, of agenerally cylindrical container according to additional exemplaryembodiments of the present disclosure;

FIGS. 31A and 31B are views of additional exemplary embodiments of acontainer according to the present teachings, wherein FIG. 31A is abottom view and FIG. 31B is a section view taken along the line 31B-31Bof FIG. 31A;

FIG. 32 is a perspective view of a mold system suitable for molding thecontainer of the present disclosure;

FIGS. 33A-33C is a series of graphs illustrating the relationshipbetween strap inclination angle and volume displacement, the number ofstraps and radial strength, and the strap peak angle and volumedisplacement.is a graph illustrating a relationship between dimensionsof a strap of the container and a volume displacement of a hot-filledcontainer;

FIG. 34 is a schematic section view of a container showing variouscurving surfaces of a central pushup portion thereof;

FIGS. 35A-35D are schematic bottom views of a central pushup portion ofa container according to teachings of the present disclosure;

FIG. 36 is a schematic section view of a container showing variousshapes for straps thereof; and

FIG. 37-39 are schematic bottom views of the container showing variousshapes for straps thereof.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings. Example embodiments are provided so that thisdisclosure will be thorough, and will fully convey the scope to thosewho are skilled in the art. Numerous specific details are set forth suchas examples of specific components, devices, and methods, to provide athorough understanding of embodiments of the present disclosure. It willbe apparent to those skilled in the art that specific details need notbe employed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a”, “an” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on”, “engaged to”,“connected to” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto”, “directly connected to” or “directly coupled to” another element orlayer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath”, “below”,“lower”, “above”, “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

This disclosure provides for a container being made of PET andincorporating a base design having an optimized size and shape thatresists container loading and pressures caused by hot fill pressure andresultant vacuum, and helps maintain container shape and response.

It should be appreciated that the size and specific configuration of thecontainer may not be particularly limiting and, thus, the principles ofthe present teachings can be applicable to a wide variety of PETcontainer shapes. Therefore, it should be recognized that variations canexist in the present embodiments. That is, it should be appreciated thatthe teachings of the present disclosure can be used in a wide variety ofcontainers, including rectangular, round, oval, squeezable, recyclable,and the like.

As shown in FIGS. 1-5, the present teachings provide a plastic, e.g.polyethylene terephthalate (PET), container generally indicated at 10.The exemplary container 10 can be substantially elongated when viewedfrom a side and generally cylindrical when viewed from above and/orrectangular in throughout or in cross-sections (which will be discussedin greater detail herein). Those of ordinary skill in the art wouldappreciate that the following teachings of the present disclosure areapplicable to other containers, such as rectangular, triangular,pentagonal, hexagonal, octagonal, polygonal, or square shapedcontainers, which may have different dimensions and volume capacities.It is also contemplated that other modifications can be made dependingon the specific application and environmental requirements.

In some embodiments, container 10 has been designed to retain acommodity. The commodity may be in any form such as a solid orsemi-solid product. In one example, a commodity may be introduced intothe container during a thermal process, typically a hot-fill process.For hot-fill bottling applications, bottlers generally fill thecontainer 10 with a product at an elevated temperature betweenapproximately 155° F. to 205° F. (approximately 68° C. to 96° C.) andseal the container 10 with a closure before cooling. In addition, theplastic container 10 may be suitable for other high-temperaturepasteurization or retort filling processes or other thermal processes aswell. In another example, the commodity may be introduced into thecontainer under ambient temperatures.

As shown in FIGS. 1-5, the exemplary plastic container 10 according tothe present teachings defines a body 12, and includes an upper portion14 having a cylindrical sidewall 18 forming a finish 20. Integrallyformed with the finish 20 and extending downward therefrom is a shoulderportion 22. The shoulder portion 22 merges into and provides atransition between the finish 20 and a sidewall portion 24. The sidewallportion 24 extends downward from the shoulder portion 22 to a baseportion 28 having a base 30. In some embodiments, sidewall portion 24can extend down and nearly abut base 30, thereby minimizing the overallarea of base portion 28 such that there is not a discernable baseportion 28 when exemplary container 10 is uprightly-placed on a surface.

The exemplary container 10 may also have a neck 23. The neck 23 may havean extremely short height, that is, becoming a short extension from thefinish 20, or an elongated height, extending between the finish 20 andthe shoulder portion 22. The upper portion 14 can define an opening forfilling and dispensing of a commodity stored therein. The container canbe a beverage container; however, it should be appreciated thatcontainers having different shapes, such as sidewalls and openings, canbe made according to the principles of the present teachings.

The finish 20 of the exemplary plastic container 10 may include athreaded region 46 having threads 48, a lower sealing ridge 50, and asupport ring 51. The threaded region provides a means for attachment ofa similarly threaded closure or cap (not shown). Alternatives mayinclude other suitable devices that engage the finish 20 of theexemplary plastic container 10, such as a press-fit or snap-fit cap forexample. Accordingly, the closure or cap engages the finish 20 topreferably provide a hermetical seal of the exemplary plastic container10. The closure or cap is preferably of a plastic or metal materialconventional to the closure industry and suitable for subsequent thermalprocessing.

In some embodiments, the container 10 can comprise a lightweight baseconfiguration 100 generally formed in base portion 28. Baseconfiguration 100 can comprise any one of a number of features thatfacilitate vacuum response, improve structural integrity, minimizecontainer weight, and/or improve overall performance of container 10. Asdiscussed herein, base configuration 100 can be used in connection withany container shape, however, by way of illustration, containers havingrectangular and cylindrical cross-sections will be examined. The baseportion 28 functions to close off the bottom portion of the plasticcontainer 10 to retain a commodity in the container 10. FIGS. 1-31Billustrate a variety of base configurations 100 and base portions 28 aswell, as will be discussed.

Referring back to FIGS. 1-5, the base portion 28 of the plasticcontainer 10, which extends inward from the body 12, can comprise one ormore contact surfaces 134 and a central portion 136. In someembodiments, the contact surface(s) 134 is the area of the base portion28 that contacts a support surface (e.g. shelf, counter, and the like)that in turn supports the container 10. As such, the contact surface 134may be a flat surface (an individual flat surface or a collection ofseparately spaced flat surfaces that each lie within a common plane. Thecontact surface 134 can also be a line of contact generallycircumscribing, continuously or intermittently, the base portion 28.

In the embodiments of FIGS. 1-5, the base portion 28 includes fourcontact surfaces 134, which are spaced away from each other about thelongitudinal axis 150 of the container 10. Also, in the embodimentsshown, the contact surfaces 134 are arranged at the corners of the baseportion 28. However, it will be appreciated that there can be any numberof contact surfaces 134 and the contact surfaces 134 can be disposed inany suitable position.

The base portion 28 can further include a central pushup portion 140,which is most clearly illustrated in FIGS. 4 and 5. The central pushupportion 140 can be centrally located (i.e., substantially centered onthe longitudinal axis 150). The central pushup portion 140 can extendgenerally toward the finish 20. In some embodiments, the central pushupportion 140, when viewed in cross section (FIG. 5), is generally in theshape of a truncated cone having a top surface 146 that is generallyparallel to the support surfaces 134. The pushup portion 140 can alsoinclude side surfaces 148 that slope upward toward the centrallongitudinal axis 150 of the container 10. The side surfaces 148 can befrusto-conic or can include a plurality of planar surfaces that arearranged in series about the axis 150.

Other shapes of the central pushup portion 140 are within the scope ofthe present disclosure. For instance, as shown in FIG. 13, the pushupportion 140 can be partially frusto-conic and partially cylindrical.Also, as shown in FIGS. 17, 23, and 25, the pushup portion 140 can begenerally frusto-conic with a plurality of ribs 171 that extend at anangle along the side surface 148 at equal spacing about the axis 150.Moreover, as shown in FIGS. 19 and 21, the pushup portion 140 can beannular, so that a depending frusto-conic projects exteriorly along theaxis 150. FIGS. 35A-35D show additional shapes for the pushup portion140 (in respective bottom views of the container 10). For instance, thetop surface 146 can be defined by a plurality of convexly curved linesthat are arranged in series about the axis (FIG. 35A), an octagon orother polygon (FIG. 35B), alternating convexly and concavely curvedlines (FIG. 35C), and a plurality of concavely curved lines (FIG. 35D).The side surface(s) 148 can project therefrom to have a correspondingshape.

As shown in FIG. 34, the top surface 146 and/or the side surface(s) 148can have a concave and/or convex contour. For instance, the top surface146 can have a concave curvature (indicated at 146′) or a convexcurvature (indicated at 146″). Additionally, the side surface 148 canhave a concave curvature (indicated at 148′), a convex curvature(indicated at 148″), or a S-shaped combination concave and convexcurvature (indicated at 148′″). This curvature can be present when thecontainer 10 is empty. Also, the curvature can be the result ofdeformation due to vacuum loads inside the container 10.

The side surface 148 can also be stepped in some embodiments. Also, theside surface 148 can include ribs, convex or concave dimples, or rings.

The exact shape of the central pushup 140 can vary greatly depending onvarious design criteria. For additional details about suitable shapes ofcentral pushup 140, attention should be directed to commonly-assignedU.S. patent application Ser. No. 12/847,050, which published as U.S.Patent Publication No. 2011/0017700, which was filed on Jul. 30, 2010,and which is incorporated herein by reference in its entirety.

The central pushup 140 is generally where the preform gate is capturedin the mold when the container 10 is blow molded. Located within the topsurface 146 is the sub-portion of the base portion 28, which typicallyincludes polymer material that is not substantially molecularlyoriented.

The container 10 can be hot-filled and, upon cooling, a vacuum in thecontainer 10 can cause the central pushup 140 to move (e.g., along theaxis 150, etc.) to thereby decrease the internal volume of the container10. The central pushup 140 can also resiliently bend, flex, deform, orotherwise move in response to these vacuum forces. For instance, the topsurface 146 can be flat or can convexly curve without the vacuum forces,but the vacuum forces can draw the top surface 146 upward to have aconcave curvature as shown in FIG. 34. Likewise, the side surfaces 148can deform due to the vacuum to be concave and/or convex as shown inFIG. 34. Thus, the central pushup 140 can be an important component ofvacuum performance of the container 10 (i.e., the ability of thecontainer 10 to absorb these vacuum forces without losing its ability tocontain the commodity, withstand top loading, etc.)

Various factors have been found for the base portion 28 that can enhancesuch vacuum performance. In conventional applications, it has been foundthat material can be trapped or otherwise urged into the pushup portionof the base. The amount of material in these conventional applicationsis often more than is required for loading and/or vacuum response and,thus, represents unused material that adds to container weight and cost.This can be overcome by tailoring the pushup diameter (or width in termsof non-conical applications) and/or height to achieve improved loadingand/or vacuum response from thinner materials. That is, by maximizingthe performance of the central pushup 140, the remaining containerportions need not be designed to withstand a greater portion of theloading and vacuum forces, thereby enabling the overall container to bemade lighter at a reduced cost. When all portions of the container aremade to perform more efficiently, the container can be more finelydesigned and manufactured.

To this end, it has been found that by reducing the diameter of centralpushup 140 and increasing the pushup height thereof, the material can bestretched more for improved performance. With reference to FIG. 5, eachcontainer 10 having pushup 140 defines several dimensions, including apushup width Wp (which is generally a diameter of the entrance ofcentral pushup 140), a pushup height Hp (which is generally a heightfrom the contact surface 134 to the top surface 146), and an overallbase width Wb (which is generally a diameter or width of base portion 28of container 10). Based on performance testing, it has been found thatrelationships exist between these dimensions that lead to enhancedperformance. Specifically, it has been found that a ratio of pushupheight Hp to pushup width Wp of about 1:1.3 to about 1:1.4 is desirable(although ratios of about 1:1.0 to about 1:1.6 and ratios of about 1:1.0to about 1:1.7 can be used). Moreover, a ratio of pushup width Wp tooverall base width Wb of about 1:2.9 to about 1:3.1 is desirable(although ratios of about 1:2.9 to about 1:3.1 and ratios of about 1:1.0to about 1:4.0 can be used). Moreover, in some embodiments, centralpushup 140 can define a major diameter (e.g. typically equalapproximately to the pushup width Wp or the diameter at the lowermostportion of central pushup 140). The central pushup 40 can further definea minor diameter (e.g. typically equal to the diameter of the topsurface 146 or the width at the uppermost portion of central pushup140). The combination of this major diameter and minor diameter canresult in the formation of a truncated conical shape. Moreover, in someembodiments, the surface of this truncated conical shape can define adraft angle of less than about 45 degrees relative to centrallongitudinal axis 150. It has been found that this major diameter orwidth can be less than about 50 mm and the minor diameter or width canbe greater than about 5 mm, separately or in combination.

In some embodiments shown in FIGS. 8 and 9, the container 10 can includean inversion ring 142. The inversion ring 142 can have a radius that islarger than the central pushup 140, and the inversion ring 142 cancompletely surround and circumscribe the central pushup 140. In theposition shown in FIGS. 8 and 9 and under certain internal vacuumforces, the inversion ring 142 can be drawn upward along the axis 150away from the plane defined by the contact surface 134. However, whenthe container 10 is formed, the inversion ring 142 can protrudeoutwardly away from the plane defined by the contact surface 134. Thetransition between the central pushup 140 and the adjacent inversionring 142 can be rapid in order to promote as much orientation as nearthe central pushup 140 as possible. This serves primarily to ensure aminimal wall thickness for the inversion ring 142, in particular at thecontact surface 134 of the base portion 28. At a point along itscircumferential shape, the inversion ring 142 may alternatively featurea small indentation, not illustrated but well known in the art, suitablefor receiving a pawl that facilitates container rotation about thecentral longitudinal axis 150 during a labeling operation.

In some embodiments, as illustrated throughout the figures and notablyin FIGS. 28A-31A, the container 10 can further comprise one or morestraps 170 formed along and/or within base portion 28. As can be seenthroughout FIGS. 1-25, straps 170 can be formed as recessed portionsthat are visible from the side of container 10. That is, straps 170 canbe formed such that they define a surface (i.e., a strap surface 173that defines a strap axis of the respective strap 170). The strapsurface 173 can be offset at a strap distance Ds (FIG. 2) from contactsurface(s) 134 in the Z-axis (generally along central longitudinal axis150 of container 10). In some embodiments, this offset Ds between straps170 and contact surface 134 can be in the range of about 5 mm to about25 mm. Also, the strap surface 173 can extend transverse to the axis 150to terminate adjacent the sidewall portion 24. The periphery of thestraps 170 can contour so as to transition into the sidewall portion 24and/or the contact surfaces 134.

At least a portion of the strap surface 173 can extend substantiallyparallel to the plane of the contact surfaces 134 as shown in FIGS. 1-4.Also, in some embodiments illustrated in FIGS. 10-12, at least a portiono the strap surface 173 can be partially inclined at a positive anglerelative to the contact surface 134. The angle can be less than 15degrees in some embodiments. The angle can be greater than 15 degrees inother embodiments.

FIG. 36 shows various shapes that the straps 170 can have. For instance,the straps can concavely contour in the transverse direction (indicatedat 170′), can convexly contour in the transverse direction (indicated at170″), or can have one or more steps in the transverse direction(indicated at 170′″).

FIGS. 37-39 show how the straps can be shaped in plan view. Forinstance, the strap can have a sinusoidal shape (indicated at 170″″ inFIG. 37) or the strap can include steps that expand or contract thestrap in the transverse direction moving away from the axis 150(indicated at 170′″″ in FIG. 37). Moreover, the strap can taper inwardor outward in the transverse direction (indicated at 170″″″ in FIG. 39).Additionally, the straps can be arranged in a pinwheel shape (indicatedat 170′″″″ in FIG. 38).

The shape, dimensions, and other features of the straps 170 can dependupon container shape, styling, and performance criteria. Moreover, itshould be recognized that the offset (along the axis 15) of one strap170 can differ from the offset of another strap 170 on a singlecontainer to provide a tuned or otherwise varied load response profile.Straps 170 can interrupt contact surface 134, thereby resulting in aplurality of contact surfaces 134 (also known as a footed or segmentedstanding surface). Because of the offset nature of straps 170 and theirassociate shape, size, and inclination (as will be discussed), straps170 is visible from a side view orientation and formable via simplifiedmold systems (as will be discussed).

It has been found that the use of straps 170 can serve to reduce theoverall material weight needed within base portion 28, compared toconventional container designs, while simultaneously providingsufficient and comparable vacuum performance. In other words, straps 170have permitted containers according to the principles of the presentteachings to achieve and/or exceed performance criteria of conventionalcontainers while also minimizing container weight and associated costs.

In some embodiments, container 10 can include at least one strap 170disposed in base portion 28. However, in alternative designs, additionalstraps 170 can be used, such as two, three, four, five, or more.Multiple straps 170 can radiate from the central pushup portion 140 andthe longitudinal axis 150. In some embodiments, the straps 170 can beequally spaced apart about the axis 150.

Typically, although not limiting, rectangular containers (FIGS. 1-28B)may employ two or more even-numbered straps 170. The straps 170 can, insome embodiments, bisect the midpoint (i.e., the middle region) of therespective sidewall. Stated differently, the strap 170 can intersect therespective sidewall approximately midway between the adjacent sidewalls.If the sidewall portion 24 defines a different polygonal cross section(taken perpendicular to the axis 150), the straps 170 can similarlybisect the sidewalls.

Similarly, although not limiting, cylindrical containers (FIGS. 29A-30B)may employ three or more odd-numbered or even-numbered straps 170. Assuch, straps 170 can be disposed in a radial orientation such that eachof the plurality of straps 170 radiates from a central point of baseportion 28 to an external edge of the container 10 (e.g. adjacentsidewall portion 24). It should be noted, however, that although straps170 may radiate from a central point, that does not mean that each strap170 actually starts at the central point, but rather means that if acentral axis of each strap 170 was extended inwardly they wouldgenerally meet at a common center. The relationship of the number ofstraps used to radial strength of container 10 has shown an increasingradial strength with an increasing number of straps used (see FIG. 23B).

It should also be noted that strap 170 can be used in conjunction withthe aforementioned central pushup 140, which would thereby interruptstraps 170. However, alternatively, it should be noted that benefits ofthe present teachings may be realized using straps 170 without centralpushup 140.

As illustrated in the several figures, straps 170 can define any one ora number of shapes and sizes having assorted dimensional characteristicsand ranges. However, it has been found that particular strap designs canlead to improved vacuum absorption and container integrity. By way ofnon-limiting example, it has been found that straps 170 can define astrap plane or central axis 172 that is generally parallel to contactsurface 134 and/or a surface upon which container 10 sits, therebyresulting in a low strap angle. In other embodiments, strap plane/axis172 can be inclined relative to contact surface 135 and/or the surfaceupon which container 10 sits, thereby resulting in a high strap angle.In some embodiments, this inclined strap plane/axis 172 can be inclinedsuch that a lowest-most portion of inclined strap plane/axis 172 istoward an inbound or central area of container 10 and a highest-mostportion of inclined strap plane/axis 172 is toward an outbound orexternal area of container 10 (e.g. adjacent sidewall portion 24).Examples of such inclination can be seen in FIGS. 26B and 27B.

Low strap angles (e.g., FIGS. 1-4) provide base flexibility resulting inbase flex that displaces volume through upward deflection. This upwarddeflection will be enhanced under vertical load providing additionalvolume displacement, transitioning to positive pressure to maximizefilled capped topload. This complementary “co-flex base” technologyprovides volume displacement & filled capped topload performance therebyresulting in a “lightweight panel-less” container configuration formulti-serve applications. Conversely, a high strap angle (e.g., FIGS.26B and 27B) provides base rigidity resulting in a base that enhancesvertical and horizontal load bearing properties. Rectangular containerdesigns provide sufficient volume displacement. This complementary“rigid-base” technology provides enhanced handling properties onfill-lines and tray distribution offerings thereby resulting in a“lightweight tray capable” container configuration for multi-serveapplications.

By way of non-limiting example, it has been found that an inclinationangle α (FIG. 19) of strap plane/axis 172 of about 0 degrees to about 30degrees (i.e. strap angle) can provide improved performance. This strapangle α can be measured in a side cross-section take along strap planeor axis 172 relative to a horizontal reference plane or axis as shown inFIG. 19. However, it should be recognized that other strap angles may beused and/or the direction of inclination can be varied. The relationshipof inclination angle α to volume displacement of container 10 has shownan increasing volume displacement with a decreasing inclination angle α(see FIG. 33A).

With particular reference to FIGS. 26A-27B, it should be noted thatstrap 170 can further define or include a secondary contour or shapewhen viewed generally along strap plane or axis 172. That is, whenviewing from the side of the container 10, the strap 170 can define apeaked shape or trapezoid shape adjacent the sidewall portion 24 havinga raised central area and downwardly extending side surfaces (see FIGS.26B and 27B) as opposed to defining a generally flat, single plane. Thetrapezoidally shaped portion can be planar also and disposed at a draftangle relative to a horizontal (imaginary) reference line. This draftangle can be between 0 degrees and 45 degrees. In some embodiments, thissection of the strap 170 can have a triangular shape that furtherprovides improved vacuum response and structural integrity whilesimultaneously permitting reduction in material weight and costs. By wayof non-limiting example, it has been found that a peak 175 of the strap170 (FIGS. 19, 26B and 27B) can define a peak angle β (FIG. 19) relativeto a vertical or perpendicular reference line in the range of about 0degrees to 90 degrees (flat strap 170). In some embodiments, peak angleβ can define a range of about 1 degree to about 45 degrees. However, itshould be recognized that other angles may be used and/or the directionand overall shape of strap 170 can be varied. The relationship of peakangle β to volume displacement of container 10 has shown an increasingvolume displacement with a decreasing peak angle β (see FIG. 23C).

In some embodiments, as illustrated in FIGS. 1, 29B, and 30B, baseportion 28 can further comprise one or more ribs 180 formed in (e.g.,entirely within) or along strap 170. Ribs 180 can include aninwardly-directed channel (recessed toward the interior of the container10) or outwardly-directed channel (projecting outward from the interiorof the container 10). Also, the rib 180 can be contained entirely withinthe respective strap 170 or can extend out of the respective strap 170in some embodiments. The ribs 180 can serve to tune or otherwise modifythe vacuum response characteristics of straps 170. In this way, ribs 180serve to modify the response profile of one or more straps 170. Withreference to the several figures, ribs 180 can follow one of a number ofpathways, such as a generally V-shaped pathway (FIGS. 29B, 30B). In someembodiments, these pathways can define a pair of arcuate channels 182terminating at a central radius 184.

The plastic container 10 of the present disclosure is a blow molded,biaxially oriented container with a unitary construction from a singleor multi-layer material. A well-known stretch-molding, heat-settingprocess for making the one-piece plastic container 10 generally involvesthe manufacture of a preform (not shown) of a polyester material, suchas polyethylene terephthalate (PET), having a shape well known to thoseskilled in the art similar to a test-tube with a generally cylindricalcross section. An exemplary method of manufacturing the plasticcontainer 10 will be described in greater detail later.

Referring to FIG. 32, exemplary embodiments of a mold system 306 forblow molding the container 10 is illustrated. The mold system 306 can beemployed for the manufacture of container geometries, namely basegeometries, that could not be previously made. As illustrated in FIG.32, in some embodiments, the mold system 306 can comprise a base system310 disposed in operably connection with a sidewall system 320. Basesystem 310 can be configured for forming generally an entire portion ofbase portion 28 of container 10 and extends radially and upward until atransition to sidewall portion 24. Base system 310, in some embodiments,can maintain a temperature that is different from sidewall system320—either hotter or colder than sidewall system 320. This canfacilitate formation of container 10 to speed up or slow down therelative formation of the base portion 28 of container 10 duringmolding.

In some embodiments, base system 310 can comprise a lower pressurecylinder to extend and retract a push up member 323 (shown in phantom inFIG. 32). The push up member 32 can be used to extend or otherwisestretch central pushup 140 axially toward the interior of the container10. As seen in FIG. 32, push up member 322 can be centrally disposed inbase system 310. Also, the push up member 322 can have a retractedposition, wherein the push up member 322 is close to flush withsurrounding portions of the base system 310, and an extended position(shown in phantom), wherein the push up member 322 can extend away fromsurrounding portions of the base system 310. In the extended position,the push up member 322 can engage the preform during forming and urgepreform upward (e.g. inwardly) to form central pushup 140. Also,following formation of central pushup 140, push up member 322 can beretracted to permit demolding of the final container 10 from the mold.In some additional embodiments, push up member 322 of base system 310can be paired with a counter stretch rod, if desired.

An exemplary blow molding method of forming the container 10 will now bedescribed. A preform version of container 10 includes a support ring,which may be used to carry or orient the preform through and at variousstages of manufacture. For example, the preform may be carried by thesupport ring, the support ring may be used to aid in positioning thepreform in a mold cavity 321 (FIG. 32), or the support ring may be usedto carry an intermediate container once molded. At the outset, thepreform may be placed into the mold cavity 321 such that the supportring is captured at an upper end of the mold cavity 320. In general, themold cavity has an interior surface corresponding to a desired outerprofile of the blown container. More specifically, the mold cavityaccording to the present teachings defines a body forming region, anoptional moil forming region and an optional opening forming region.Once the resultant structure (hereinafter referred to as an intermediatecontainer) has been formed, any moil created by the moil forming regionmay be severed and discarded. It should be appreciated that the use of amoil forming region and/or opening forming region are not necessarily inall forming methods.

In one example, a machine (not illustrated) places the preform heated toa temperature between approximately 190° F. to 250° F. (approximately88° C. to 121° C.) into the mold cavity. The mold cavity may be heatedto a temperature between approximately 250° F. to 350° F. (approximately121° C. to 177° C.). A stretch rod apparatus (not illustrated) stretchesor extends the heated preform within the mold cavity to a lengthapproximately that of the intermediate container thereby molecularlyorienting the polyester material in an axial direction generallycorresponding with the central longitudinal axis of the container 10.While the stretch rod extends the preform, air having a pressure between300 PSI to 600 PSI (2.07 MPa to 4.14 MPa) assists in extending thepreform in the axial direction and in expanding the preform in acircumferential or hoop direction thereby substantially conforming thepolyester material to the shape of the mold cavity and furthermolecularly orienting the polyester material in a direction generallyperpendicular to the axial direction, thus establishing the biaxialmolecular orientation of the polyester material in most of theintermediate container. The pressurized air holds the mostly biaxialmolecularly oriented polyester material against the mold cavity for aperiod of approximately two (2) to five (5) seconds before removal ofthe intermediate container from the mold cavity. This process is knownas heat setting and results in a heat-resistant container suitable forfilling with a product at high temperatures.

Alternatively, other manufacturing methods, such as for example,extrusion blow molding, one step injection stretch blow molding andinjection blow molding, using other conventional materials including,for example, high density polyethylene, polypropylene, polyethylenenaphthalate (PEN), a PET/PEN blend or copolymer, and various multilayerstructures may be suitable for the manufacture of plastic container 10.Those having ordinary skill in the art will readily know and understandplastic container manufacturing method alternatives.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

What is claimed is:
 1. A heat-set container that defines a longitudinalaxis comprising: a finish; a sidewall portion extending from saidfinish; a base portion extending from said sidewall portion andenclosing said sidewall portion to form a volume therein for retaining acommodity, said base portion having a plurality of contact surfaces forsupporting the container, said plurality of contact surfaces spaced awayfrom each other about the longitudinal axis; and a central pushupportion disposed in said base portion and extending generally toward thefinish, said central pushup portion being substantially centered on thelongitudinal axis, said central pushup portion being moveable inresponse to internal vacuum pressure to decrease said volume.
 2. Theheat-set container according to claim 1 wherein said central pushupportion has a generally frusto-conic shape.
 3. The heat-set containeraccording to claim 2 wherein said central pushup portion comprises anupper surface spaced apart from said contact surface in a directionparallel to the longitudinal axis to define a pushup height, saidcentral pushup portion defining a pushup entrance having a pushup width.4. The heat-set container according to claim 3 wherein said centralpushup portion is sized such that a ratio of said pushup height to saidpushup width is in the range of about 1:1.3 to about 1:1.4.
 5. Theheat-set container according to claim 3 wherein said central pushupportion is sized such that a ratio of said pushup height to said pushupwidth is in the range of about 1:1.0 to about 1:1.6.
 6. The heat-setcontainer according to claim 3 wherein said central pushup portion issized such that a ratio of said pushup height to said pushup width is inthe range of about 1:1.0 to about 1:1.7.
 7. The heat-set containeraccording to claim 3 wherein said central pushup portion is sized suchthat a ratio of said pushup width to an overall width of said baseportion is in the range of about 1:2.9 to about 1:3.1.
 8. The heat-setcontainer according to claim 3 wherein said central pushup portion issized such that a ratio of said pushup width to an overall width of saidbase portion is in the range of about 1:2.5 to about 1:3.5.
 9. Theheat-set container according to claim 3 wherein said central pushupportion is sized such that a ratio of said pushup width to an overallwidth of said base portion is in the range of about 1:1 to about 1:4.10. The heat-set container according to claim 1 wherein said centralpushup portion is generally conical extending from a major width to aminor width.
 11. The heat-set container according to claim 10 whereinsaid major width is generally less than about 50 mm.
 12. The heat-setcontainer according to claim 10 wherein said minor width is generallygreater than about 5 mm.
 13. The heat-set container according to claim10 wherein said conical shape defines a pushup wall angle of less thanabout 45 degrees relative to the longitudinal axis.
 14. The heat-setcontainer according to claim 1, wherein the central pushup portion caninclude a top surface that is centered on the longitudinal axis and aside surface that extends away from the top surface toward the contactsurfaces, wherein the at least one of the top surface and the sidesurface changes in contour in response to internal vacuum pressure. 15.The heat-set container according to claim 14, wherein the at least oneof the top surface and the side surface is convexly curved.
 16. Theheat-set container according to claim 14, wherein the at least one ofthe top surface and the side surface is concavely curved.
 17. Theheat-set container according to claim 1, wherein the central pushupportion includes a top surface that is defined by a plurality of linesthat are arranged about the longitudinal axis, the plurality of linesarranged in one of a polygonal shape, a plurality of convex curves, aplurality of concave curves, and an alternating arrangement of convexand concave curves.
 18. A mold system for forming a heat-set containerhaving a central pushup portion disposed in a base portion thereof, thecentral pushup portion substantially centered on a longitudinal axis ofthe container and extending generally toward an interior of thecontainer, the base portion having a plurality of contact surfaces forsupporting the container, said plurality of contact surfaces spaced awayfrom each other about the longitudinal axis, the base portion bound by asidewall portion to hold a commodity, said mold system comprising: asidewall system for molding the sidewall portion of the container; and abase system for molding the base portion of the container, said basesystem operable to form an entirety of the base portion of the containerincluding the central pushup portion and the plurality of contactsurfaces.
 19. The mold system according to claim 18, further comprising:a pushup member operably coupled with said base system, said pushupmember being movable being an extended position and a retractedposition, said pushup member stretching the central pushup portion ofthe container in said extended position, said pushup member beingseparate from the central pushup portion of the container in saidretracted position.
 20. The mold system according to claim 18 whereinsaid base system is at a first temperature and said sidewall system isat a second temperature, said first temperature being different thansaid second temperature.
 21. The mold system according to claim 20wherein said first temperature is higher than said second temperature.22. The mold system according to claim 20 wherein said first temperatureis lower than said second temperature.
 23. The mold system according toclaim 18 wherein said base system is bound by said sidewall system.